Repeated pulses of volcanism drove the Late Triassic Carnian Pluvial episode

Multiple consecutive global environmental and biological changes during the Late Triassic Carnian Pluvial Episode (CPE; ∼234–232 Ma) are thought to have been triggered by pulses of greenhouse gas emissions from Large Igneous Province (LIP) volcanism. However, the lack of high-resolution paired geochemical records of cycle disruption and volcanism pinned to cyclostratigraphic frameworks impedes estimates of the tempo of LIP emissions and associated climate changes. Our new astronomical timescale from terrestrial strata in the Jiyuan Basin (North China) reveals that the CPE lasted for approximately 1.65 Myr, encompassing four 405 kyr long eccentricity cycles. Each 405 kyr long eccentricity cycle was accompanied by coupled negative excursions of organic carbon isotopes (δ13Corg) and near-zero Δ199Hg values that indicate synchronous C-cycle perturbations and volcanic Hg deposition. This allows linking the consecutive environmental changes observed in the terrestrial succession of North China to distinct volcanic pulses of Wrangellia LIP. Our results show that in addition to the effects of Wrangellia LIP, orbital forcing, i.e. the 405 kyr long eccentricity, may have amplified the global climatic disturbances during the CPE.